Antenna arrangement, especially for radio beacons



D. ERBEN July 16, 1940.

ANTENNA ARRANGEMENT, ESPECIALLY FOR RADIO BEACONS Filed April 21, 1938 2 Sheets-Sheet 1 D. ERBEN ANTENNA ARRANGEMENT, ESPECIALLY FOR RADIO BEACONS 2 Sheets-Sheet 2 Filed April 21, 1938 m mm 0 m m g a VM w 7 M m 2 w W w 7 2 2 f c Wm 0 o a 0 E w a 2 u w Z m y 9 w Patented July 16, 1940 UNITED STATES PATENT GFFICE ANTENNA ARRANGEMENT, ESPECIALLY FOR RADIO BEACONS Dietrich Erben,

Berlin-Mariendorf, Germany,

assignor to C. Lorenz Aktiengesellschaft, Berlin-Tempelhof, Germany 10 Claims.

.The invention concerns a new antenna arrangement for radio beacons which avoids disturbance of the radiation fields by the high frequency feeder and the key conductors.

In radio beacons having a continuously fed pair of vertical electrodes and two reflecting antennae which are keyed alternately in such a manner that they are alternately made effective and ineffective, there is the disadvantage that the directional characteristics become distorted by the feeder of the electrodes and the leading wires to the key relays and give rise to errors in determining the direction of the beacon signals. This is mainly due to the fact that when feeding in the current loop of the above mentioned electrodes, the radiation field is interfered with by the feeder and key-currents which have an absorbing or reflecting influence.

By means of this invention, the aforesaid disadvantage is overcome by feeding the electrodes through a reactance coil which has been noninductively wound and which is located at the junction between the emitting part of the energy transmitter, namely, the pair of electrodes, and the non-emitting part or feeder thereof. By means of this reactance coil, currents in opposite phase relation may flow through without hindrance whilst waves of the same phase which are reflected by the antenna system are choked. This prevents the feeder itself from emitting energy whilst in addition, the feeding circuits are not influenced at all.

According to a further characteristic of the invention, the electrodes are fed at one end, for example, at the lower end. For this purpose, the electrodes consist of a tube or the like of a quarter of a wave length and a conductor which is positioned in this tube.

The disturbing influence of the key conductors is overcome by extending these conductors through the lower part of the electrodes which lower part is of tubular formation.

According to a further characteristic of this invention, the high frequency feeder is also adapted to be employed as a conductor for the low frequency key frequency current. For this purpose filters are provided for preventing the high frequency current from influencing the conductors of the key relays.

Referring to the drawings which form part of this specification:

Figs. 1, 2 and 3 are diagrammatic illustrations of two practical examples of radio beacon antenna arrangements in accordance with the invention.

The transmitting radiator of the arrangement shown in Fig. 1 consists of a tube or the like I as one electrode of the dipole and a conductor 2, which is located within said tube and extends beyond said tube to form the other electrode of said radiating dipole. The feeding of the electrodes is obtained by means of a coupling at the lower end of the electrodes, namely, at the points 3, 4 through a reactance coil 5 which has been wound non-inductively. The energy conductors I screened by a jacket 8 are connected to the transmitter 6.

The keying of the reflectors 9, I0 is obtained by a working relay I I and a stationary relay I2. The key frequency is supplied to the relays II, I2 by a special key conductor passed through the tubular part I of the electrodes.

According to the embodiment illustrated in Fig. l, the high frequency feeders I and the tubular part I of the electrodes are also employed as conductors for the low frequency key frequency current. At the feeding point for this purpose coils I3, I4 are provided, the terminals I5, I6 of which are connected with the high frequency conductors I at the points I'I, I8. These high frequency conductors are connected with an oscillating circuit containing the capacity 30 and the coil 3|.

The conductors 28, 29 of the relays II, 12 are connected to the terminals I9, 20 of the electrodes l, 2. The reactance coils 2| to 26 are connected to these conductors 28, 29. Said coils 2| to 2B are wound bifilarly or unifilarly depending upon their position and type of connection. By means of these coils a horizontally polarised disturbing emission of the key conductor is avoided.

Sometimes it is important to make an outside connection of the centre point 21, for instance, to regulate the closing and opening times of the relays by the connection of resistances. This connection is made by a conductor 28' which also passes through the tubular part I of the electrodes and is choked by a winding of the noninductively wound reactance coil 5 itself or by a special reactance coil. The conductor 28' is connected for instance, to terminal 30 through the jacket 8 of the feeders I.

In the embodiment illustrated in Fig. 2, the feeder cable I consists of a conductor and a screening jacket both of which are used for the conduction of the high frequency current to the electrodes. The lower part I of the electrodes consists of portion of this screening jacket. The upper part 2 of the electrodes consists of an interior conductor projecting beyond the screening jacket for a quarter of a wave length.

The lower end. of the electrodes l, 2 formed by the high frequency cable is connected to the bifilar reactance coil 5 which is constructed simply by coiling the feeding cable. By means of this reactance coil, that part of the cable l which is adapted to function as the electrodes, is separated from the other part of the cable acting as a feeder. The key frequency is also conducted to the cable 8'.

In the transmitter 5, the high frequency current is conducted to the covering of the cable 5' at the terminal ll and to the interior conductor 2' of the cable at the terminal 18 through the oscillating circuit 3@, 3|. The low frequency key frequency current is conducted to the reactance coils 53, id from the terminals l5, l6. The frequency passing through the terminals l9, 2!) of the electrodes i, 2 is connected to the key relays ll, l2 of the reflectors 9, ill by means of the key conductors 28, 29. In order to check a horizontally polarised emission of the conductors 28, 29, reactance coils 2! to 26 are connected to these conductors.

A multi-core cable may also be used as a feeder as shown diagrammatically in Fig. 3. For ex ample, the metallic covering and one core of a three core cable may be used as high frequency conductors and as transmitting electrodes whilst the two other interior conductors may be used as key conductors. In case there is one point, for instance, the centre 27, to be connected to the two key relays H, 22 the feeder may contain one more key conductor.

The bifilar reactance coil 5 and the other reactance coils may be improved by inserting therein a core of iron suitable for use at high frequencies.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

r 1. A dipole antenna structure for producing symmetrical radiant action comprising, a tubular conductor forming oneelectrode of said dipole, a second conductor in said tubular conductor extending beyond one endof said tubular conductor to form the other electrode of said dipole, means for energizing said dipole, comprising a high frequency energy source, lead-in conductors connecting said source to said tubular member and said second conductor, and reactive means between said lead-in conductors and said tubular member and said second conductor for isolating said dipole from said conductors to prevent distortion of the radiated pattern by said lead-in conductors.

2. A dipole antenna structure according to claim 1, in which said lead-in conductor con prises a coaxial transmission line forming a continuation of said tubular member and said conductor, and said reactance means comprises a coil made by coiling a portion of said coaxial transmission line.

3. An antenna array for radio beacons comprising a radiating dipole comprising ,a tubular conductorforming one electrode of said dipole, a second conductor within said tubular conductor and extending beyond one end of said tubular conductor to form the other arm of said dipole, two reflectors arranged in spaced relation on either side of said dipole, means for alternately keying said reflectors to produce intersecting patterns, a source of radio frequency energy, conductor leads from said source to the conductors of said dipole for energizing said dipole, and reactance means between said dipole conductors and said leads for isolating said dipole from said leads.

4. An antenna array according to claim 3, in

. which said keying means comprise relays, further comprising means for applying keying control energyto said conductive leads, and a circuit between said tubular conductor, said second conductor, and said relays for conveying said control energy to said relays.

5. An antenna array according to claim 3, in which said conductor leads comprise a coaxial transmission line forming a continuation of said tubular member and said second conductor, and said reactance comprises a coil made by coiling a portion of said coaxial line.

6. An arrangement according to claim 3, wherein the dipole electrodes are fed at one end thereof, and said keying means comprises relays, further comprising additional conductors extending through said tubular electrode for controlling said relays. I

7. An arrangement'according to claim 3, further comprising a feeder, wherein said feeder and one part of the electrodes are employed as conductors for operating said keying means, a

9. An arrangement according to claim 3 wherein the dipole electrodes are fed by a coupling at one end of the electrodes, further comprising a source of keying frequency, key frequency leads connected to said keying means and to said dipole electrodes, said key frequency source being connected to said high frequency leads whereby said high frequency feeder and part of the dipole electrode are employed as conductors for the key frequency current, a plurality of filters included in the key leads and high frequency conductor leads to isolate the high frequency and low frequency apparatus from each other, said reactance 

